/**
 *
 * htmlParser改造自: https://github.com/blowsie/Pure-JavaScript-HTML5-Parser
 *
 * author: Di (微信小程序开发工程师)
 * organization: WeAppDev(微信小程序开发论坛)(http://weappdev.com)
 *               垂直微信小程序开发交流社区
 *
 * github地址: https://github.com/icindy/wxParse
 *
 * for: 微信小程序富文本解析
 * detail : http://weappdev.com/t/wxparse-alpha0-1-html-markdown/184
 */
// Regular Expressions for parsing tags and attributes

const startTag = /^<([-A-Za-z0-9_]+)((?:\s+[a-zA-Z0-9_:][-a-zA-Z0-9_:.]*(?:\s*=\s*(?:(?:"[^"]*")|(?:'[^']*')|[^>\s]+))?)*)\s*(\/?)>/
const endTag = /^<\/([-A-Za-z0-9_]+)[^>]*>/
const attr = /([a-zA-Z0-9_:][-a-zA-Z0-9_:.]*)(?:\s*=\s*(?:(?:"((?:\\.|[^"])*)")|(?:'((?:\\.|[^'])*)')|([^>\s]+)))?/g

function makeMap(str) {
    const obj = {}
    const items = str.split(',')
    for (let i = 0; i < items.length; i += 1) obj[items[i]] = true
    return obj
}

// Empty Elements - HTML 5
const empty = makeMap(
    'area,base,basefont,br,col,frame,hr,img,input,link,meta,param,embed,command,keygen,source,track,wbr'
)

// Block Elements - HTML 5
const block = makeMap(
    'address,code,article,applet,aside,audio,blockquote,button,canvas,center,dd,del,dir,div,dl,dt,fieldset,figcaption,figure,footer,form,frameset,h1,h2,h3,h4,h5,h6,header,hgroup,hr,iframe,ins,isindex,li,map,menu,noframes,noscript,object,ol,output,p,pre,section,script,table,tbody,td,tfoot,th,thead,tr,ul,video'
)

// Inline Elements - HTML 5
const inline = makeMap(
    'a,abbr,acronym,applet,b,basefont,bdo,big,br,button,cite,del,dfn,em,font,i,iframe,img,input,ins,kbd,label,map,object,q,s,samp,script,select,small,span,strike,strong,sub,sup,textarea,tt,u,var'
)

// Elements that you can, intentionally, leave open
// (and which close themselves)
const closeSelf = makeMap('colgroup,dd,dt,li,options,p,td,tfoot,th,thead,tr')

// Attributes that have their values filled in disabled="disabled"
const fillAttrs = makeMap(
    'checked,compact,declare,defer,disabled,ismap,multiple,nohref,noresize,noshade,nowrap,readonly,selected'
)

function HTMLParser(html, handler) {
    let index
    let chars
    let match
    let last = html
    const stack = []

    stack.last = () => stack[stack.length - 1]

    function parseEndTag(tag, tagName) {
        // If no tag name is provided, clean shop
        let pos
        if (!tagName) {
            pos = 0
        } else {
            // Find the closest opened tag of the same type
            tagName = tagName.toLowerCase()
            for (pos = stack.length - 1; pos >= 0; pos -= 1) {
                if (stack[pos] === tagName) break
            }
        }
        if (pos >= 0) {
            // Close all the open elements, up the stack
            for (let i = stack.length - 1; i >= pos; i -= 1) {
                if (handler.end) handler.end(stack[i])
            }

            // Remove the open elements from the stack
            stack.length = pos
        }
    }

    function parseStartTag(tag, tagName, rest, unary) {
        tagName = tagName.toLowerCase()

        if (block[tagName]) {
            while (stack.last() && inline[stack.last()]) {
                parseEndTag('', stack.last())
            }
        }

        if (closeSelf[tagName] && stack.last() === tagName) {
            parseEndTag('', tagName)
        }

        unary = empty[tagName] || !!unary

        if (!unary) stack.push(tagName)

        if (handler.start) {
            const attrs = []

            rest.replace(attr, function genAttr(matches, name) {
                const value =
                    arguments[2] ||
                    arguments[3] ||
                    arguments[4] ||
                    (fillAttrs[name] ? name : '')

                attrs.push({
                    name,
                    value,
                    escaped: value.replace(/(^|[^\\])"/g, '$1\\"') // "
                })
            })

            if (handler.start) {
                handler.start(tagName, attrs, unary)
            }
        }
    }

    while (html) {
        chars = true

        if (html.indexOf('</') === 0) {
            match = html.match(endTag)

            if (match) {
                html = html.substring(match[0].length)
                match[0].replace(endTag, parseEndTag)
                chars = false
            }

            // start tag
        } else if (html.indexOf('<') === 0) {
            match = html.match(startTag)

            if (match) {
                html = html.substring(match[0].length)
                match[0].replace(startTag, parseStartTag)
                chars = false
            }
        }

        if (chars) {
            index = html.indexOf('<')
            let text = ''
            while (index === 0) {
                text += '<'
                html = html.substring(1)
                index = html.indexOf('<')
            }
            text += index < 0 ? html : html.substring(0, index)
            html = index < 0 ? '' : html.substring(index)

            if (handler.chars) handler.chars(text)
        }

        if (html === last) throw new Error(`Parse Error: ${html}`)
        last = html
    }

    // Clean up any remaining tags
    parseEndTag()
}

export default HTMLParser
